Tanks placed on the beds of pick-up trucks have long been used to transport liquids. Such tanks can be made of a variety of materials, however, one-piece truck tanks can molded out of polyethylene, or some other type of thermoformed or rotomolded thermoplastic. Plastic tanks are increasingly popular due to their strength, lack of joints or seams to leak, ability to carry potable drinking water, low cost and corrosion-resistance.
Large capacity thermoplastic tanks all have a substantially flat bottom which engages with the truck's bed for supporting the weight of stored liquid. For example, American Tank Company of Windsor, Calif., U.S.A. manufactures flat-bottomed rectangular and dome-top pick-up truck tanks in a variety of sizes. These tanks can hold from 180 to 425 US gal.; of liquid and are rated for liquids weighing up to 12.5 lbs. per US gal.; holding from 2100 to 5000 pounds of liquid or more when full.
Pick-up trucks may also be provided with trailer hitches which, rather than mounting to the rear of the vehicle, are secured to the bed or frame of the truck approximately between the wheel wells. These bed-mounted types of hitches come in a variety of designs, including the commonly known fifth wheel hitches and goose neck hitches. While these types of hitches provide greater towing capacity, they also preclude the use of these large capacity flat-bottomed thermoplastic truck tanks without removal of the hitch. This is especially true for the fifth wheel type of hitch, which may take up most of the volume or space between the wheel wells. Goose-neck hitches typically have a ball extending 4 to 5 inches upwardly from the bed between the wheel wells, which preclude the use of the traditional large capacity flat-bottomed thermoplastic truck tanks; as they can puncture the tank.
Goose-neck hitches are an especially popular type of hitch for towing horse trailers and are therefore often installed on agricultural work trucks. As a work truck is often used alternately between towing a trailer and hauling tanks of liquid such as water, a goose-neck hitch becomes a common impediment to the installation of the tank. Typically, one must first remove the goose-neck's ball and any ancillary components so as to permit a flat-bottomed truck tank to be placed on the bed of the work truck.
Some goose-neck hitches are configured to address this issue by being able to fold under the bed, leaving a flat area. However, these folding goose-neck hitches quickly become rusted and seize up; especially when the truck bed is exposed to the elements.
One solution is to use smaller capacity tanks placed on an area of the truck bed not occupied by the hitch. For example, Diverse Plastic Tanks Inc. of Mississauga, Ontario, Canada, manufactures a 72-gallon U-shaped pick-up truck tank for placement behind a fifth-wheel hitch and under the trailer. The U-shaped tank does not hold as large a capacity of liquid as do the tanks of the American Tank Company described above, simply because of the smaller dimension required to fit behind the fifth-wheel hitch.
Another solution is to use a tank which has a base foot-print small enough to fit in front of, or behind, a fifth wheel hitch, but which has an increased capacity by virtue of increased height. High profile tanks however have a higher center of gravity, preclude rear vision through the back of a truck's cab and result in decreased aerodynamics.
What is needed is a large capacity thermoplastic truck tank which can be placed on a pick-up truck's bed, whether or not a bed-mounted hitch is present, having a lower center of gravity and providing for rear vision.